There is definitely a little bit of crossover between the styles. You'll have some really big, really hoppy IPAs, and some drier, lower ABV Doubles, and the numbers might seem similar.

You have to judge it more based on what's in the glass. Double IPAs will have a definitely alcohol presence, IPAs might, but it won't be as strong (Neither should be assertive, just a nice warming). Doubles will be much more bitter. You're really looking for that tongue-stripping bitterness. Doubles will also be extremely hoppy. Hops should really, completely, dominate the beer.

In terms of numbers: Firestone walker Union Jack is 7.5 ABV, Green Flash IPA is 7 or 7.1%. Stone's Ruination (Double IPA) is 7.7% For me IPAs are usually under 7.5% and Doubles are usually over 8%, but there's obviously some wiggle room.

But ruination is much more bitter than a union jack, and the union jack has a more pronounced malt character. Ruination is just straight hops.

That's mostly how I think of it. Double IPAs are a showcase for hops. just all hops. IPAs, while being very hoppy, still strike a balance with the malt.

You'll just have to taste the beer. Personally I'd say that's a big IPA, not quite DIPA.

But honestly, what does it matter? Call it whatever you feel like it is.

You know, it really doesn't matter 90% of the time. I usually just write IPA and the bottling date on the cap and it's gone in a month anyways. I like to come up with clever labels for the ones I give to friends sometimes though, some of whom are beer snobs. That being said, even the BJCP guidelines show an awful lot of overlap between these two styles.

For me a DIPA needs to be at least 7.5%, leaning more toward 8%+. The more alcohol you have, the more hops you need to balance it out (usually). Just because something is highly hoped, I don't consider it a DIPA. I like to see the alcohol content to go along with it. That's my take on it.

If you're slightly below the ABV range for IIPA (depending on the calculator), but well above the IBU range for IPA, which way do you go, or are you outside of style on both (not that it really matters)?